Water shut-off method and composition for wells



v. w. DAVlD 2,213,039

WATERSHUT-OFF METHOD AND COMPOSITION FOR WELLS Aug. 27, 1940.

Fired Nov. 14, 1938 O//zer farma/fons Wafer-.Sand

.Sha/e l /Of/ Sand @AV/b IN VENTOR A TTORNE Y rafa-@Mug gv, 1940 i UNITED STATE wA'rEasnU'r-.OFF METHOD AND como -srrIoNron WELLS v vein w. Davia, Bakersfield, Calif. Application November 14, 1938, Serial VNo. 240,311

Claims.

in certain practices, as hereinafter identified.

The present invention lin one of its aspects coritemplates a composition of rmatter adapted to take the place of ordinary cement, such as used in oil wellsj, when it becomes necessary to cement Y oi `a string ofA casing for any reason whatsoever.

More particularly, the present invention may cooperate with -iny invention described in a copend- 'ing application entitled Formation sealing composition and method o f using same, Serial -No.

2 16,098,1e`d June 2'7,\ 1938, in the United States Patent omce. t

In the' invention just identiiied, I have pro- Qposed a composition which acts as a. medium for eiectively shutting oil Water in formation Withoutappreciably affecting oil bearing sands. The

present invention is adapted to be utilized in an embodiment of the invention, after the material describedjn my first mentioned invention has been used. f

An object of .the present invention is to pro-l vide a composition `which will eectively seal formation under adverse-conditions.' By adverse conditions, I mean a composition which is capable .of setting and becoming water-resistant where the water is strongly alkaline or saline in nature, or where the water is hot. In fact, an object of the present invention is to provide a composition which will set'in the majority of cases where cement slurry could not possibly set.

' `.Another object is the provision of a composition which-will have an initial set within forty (40) Y minutes'to two (2) hours. This initial set dep ends upon the depth to which the composition is to be pumped. and such well conditions as have to do with temperature and pressure. However, o knowing the conditions', thereadness to set is controlled bythe initial viscosity of thefcom-u position to be used. l

Another object is the provision of a composition which is set.`,.

Another object is the provision of acornposition for use in wells which will have-a deiinite hard set within eight (8) to sixteen (16) hours.

Another object is the provisionoi a composition adapted to allow a well operator to resume drill'- ing within a short'perlod ofv time after casing has been landed. With respect tothe last named object, itis ordinary practice in cementing operations to-cement around a 'casing' and then allowV water Aimpervious from its initial the cement to harden aroundv the casing Vfora' number of days prior to resumingv well drilling operations' The present invention overcomes this Vlong delay inshutting down a wellbeing drilled. For the purpose of illustrating an embodiment of the invention,v

ltions are utilized.

The figure is a vertical sectional view oi a well hole containing the composition of this invention and likewise illustrating the method oi shutting` off water.

Referring to the drawing, I havev shown a well hole I within which is received a casing 2. Be-'- tween the casing and the well hole, I have pumped a material 3 adapted to function in the capacity4 of a water shut off medium. Anyusual or ordinary method whereby material may ybe pumped 4from the surface' of a well holedownwardly .through the casing and upwardly betweenthe casing and the formation may be utilized. I prel. fer to provide material for that designatedas 3 of the character described in my copending application Serial No. 216,098. Specically,` in said copending application for patent, I combine the following ingredients with clay calculated on a dry basis:

Parts by weight jClay y100 24-ho ur cement 10.5 Calcium chloride i l1 Unslakedlime 8 Prepared bentonite (para-gel) 8 25 Lithargel ..5 Flake caustic v .05

In actual use and service, the clay is thoroughly mixed with water to the consistency of a jelly `and the Stormer viscosity is in excess oi centipoises. For convenience, I term'this material ascomposition #1.

The-composition of the present invention, which I term composition #2,-comprises the following Parts'by weight Clay 25 Cement -..1.a 85% Calcium chloride i 11 Unslaked lime 8 Prepared bentonite.(paragel) 8 Litharge- For a two (2') ton mix,

the following propor- Pounds 24 .hour cement 2110 Calcium chloride 220 'Unslaked lime 160 'Prepared bentonite 160 Litharge 10 Using the formula above set forth either for a two (2) ton mix or by parts, the said materials#l are thoroughly admlxed in any well known manner and water added. Forinstance, assuming the two (2) ton mix, the/ materials designatedl are thoroughly mixed with varying amounts of water, depending uponthe initial viscosity of the liquid composition to be pumped into the'weli.

After thorough mixing, I add tothe composition a0 `position #l as indicated at 3.

750 pounds of clay and 2250 pounds of ZAL-hour cement, in dry form. The completed composition is now ready for use in a well hole.-

I have found that the amount of water which must 'oe-added to the two (2) ton mix varies with the depth of the ywell hole. It has been found by graphic analysis'that'the number of barrels 'of water used with respect to the depth of hole is astraight line, and that if initially 2% barrels of water to a two (2) ton mix is necessaryfor a 500 foot depth of hole, that for all other depths a straight Iin'ereading may be obtained, for instance:

2,000 feet depth 3 barrels of water; 3,500 feet depth 3.5 barrels of water; 8,000 feet depth 5 barrels of water: and so on.' l

flhe operation, uses and advantages of the composition just described, as -well as its advantages with relation to composition #1, are as follows:

Whilel deem it preferable to use composition #lin place of cement, still it is possible in the practice of the present invention to utilize cement' slurry between the periphery of the casing and the wall of the hole. As is general practice, the casing carries at'its lower end a shoe 4. rThis shoe is .landed upon the formation and the casing may be filled with a denite quantity of com- There is immediately pumped on top of composition #l contained within said casing, a quantity of composition #2 indicatedat 5. A frangible plug 6, of some type, to-wit, one which is easily breakable or may* be drilled, such as a wooden plug, is then placed'on' top of composition #2, and the usual hydraulic means applied for forcing the plug and the two compositions downwardly within the cas` ing/ During this movement, the casing is constantly moved up and down slowly so as to prevent any freezing of the casing within' the well im' hole and to assure that composition #l is owfrangible member. may continue, followed by the lowering of a liner Y within the casing, as is evident to any one skilled ing properly between the periphery of the casing and the wall of the hole. The well operator readily determines from his pump the instant that the plug strikes the bottom of the well hole. When this occurs, the casing is landed so that the compositions cannot again enter the casing. Also,

the water: which is usually used for driving the plug may remain Within the casing to prevent any upward movement of the plug.' Composition #1 will remain in place andtend to shut off the water sands, although not appreciably affecting the Oil sands. Composition #2 will form itself about thecasing shoe and a portion of the casing and extend into the formation. After the compositions have been allowed to set for a given time, i drilling of the well may proceed, if necessary, and

to this end, a bit may be lowered within the casing to drill out the wooden plug or break up the Further drilling of the well in this art.

As stated, I need not use composition#1, but composition #2 provides a rapid hardening water-impervious material which may be placed around the casing and its shoe, to the end that a resumption of drilling operations, if necessary, may be had within a short period of time.

'I claim: e

1. A new composition of matter comprising the reaction product of relatively small amounts of clay, twenty-four houry cement, calcium chloride,

unslaked lime, bentonite,'lithage and water, and Yadding thereto relatively large amounts of dry powdered clay and dry powdered twenty-four hour cement, whereby the iinal composition of matter is of a pumpable iluid consistency having an initial setting period of from 40 to 120 minutes. 2. A new composition of matter comprising the y reaction product consisting of parts by weight of clay, 851/2 parts by weight of twenty-four hour cement, 1 ,1 parts by weight of calcium chloride,

8 parts by weight of unslaked lime. 8 parts by. weight of bentonite and 1/2 part by weight of lithage and water, admixed with 37.5 parts by Weight of dry powdered clay and `112.5 parts by weight of dry powdered twenty-four hour cement,

,whereby the resultant product is'of a. pumpable fluid consistency having an initial setting period of from 40 to 120 minutes.

3. The method of preparing a pumpable fluid Vunslalied lime, prepared bentoniteand lithage with a predetermined quantity of Water,'which y quantity of water is determined by the depth of the well hole in which it is to be used, to form a iiuid reaction product, adding to such reaction product in dry form relatively large amounts oi clay and twenty-four hour cement, and then ad'- mixing the mass into a homogeneous product.

5.The method of preparing -a pumpable uid composition product for use as a water' shut-off in wells which comprises thoroughly admiin'ng 25 parts by weight of clay, 851/2 partsby Weight of twenty-four hour cement, 11 parts by weight of calcium chloride, 8 parts by Weightv of unslaked lime, and 1/2 Ipart by weight of lithage with a predetermined quantity of Waterfwhich de-- ends upon the depth-of the well hole in which the product is to be pumped, to form a reactionproduct, adding to such reaction product in dry powdered form, 37.5 parts by Weight of dry powdered clay, and 112.5- parts by weight of dry powdered twenty-four hour cement, and. then acl-lA mixing the mass into a homogeneous product. VERN W. DAVID. 

